PHOTOS: Mongolia Gold Rush Destroying Rivers

Herders and miners stop for a drink of water at a natural spring near the Gold East quarry in Zaamar, Mongolia, July 2005.

In scenes reminiscent of the U.S. Wild West, many of the mining sites abandoned by larger companies have been taken over by small-scale miners known as ninjas.

"These newly formed camps are not supported by government social programs, and this unregulated mining furthers the environmental concerns," said Bob Harris, who sits on the board of directors of the Tahoe-Baikal Institute, a nonprofit environmental group based in Siberia.